I don't get this.
A drysuit is a bag with a zipper. My first DS was bought off of eBay. My next one wasn't because I got the deal of the decade. I'd buy a used drysuit way before I'd buy used regs, or a used BC.
That said, 99.9% of my gear has come off of eBay. My regs, wifie's regs, my BP/W, fins, lights, compasses, computers, bags, blah, blah. All without a single issue.
Drysuits are cheap to fix (presuming the zipper is working.) Seal replacement is simple, patching is even easier. I don't get the hesitation. If the seller if your size (hee hee...or was your size) what's the deal? They're much easier to repair than a BC.
As to regs - please. I'd buy a used one off of eBay in a moment, if the price was right. Re-build kits are cheap, and you're not paying the inflated retail prices or the consumer acquisition expenses of the manufacturer or dealer...or for that matter, the pretty box. Factory Warranties on these things are overrated, especially seeing as you take them in every year to get checked and serviced anyway. DA is right on the money - good condition, recent model regs are one of the treasures of eBay.
Scubafreak - I get your point... the whole "peace of mind" thing. And I'm a nut about caring for my gear. But I tell you what, I've dropped my regs a number of times. I'd stepped on the hose, and bounced the first stage... and they breathe great and perform perfectly 6 years later. The minute someone opens it up and screws it on, its used. And most of that used eBay stuff (when carefully selected) will be much less used and abused than my own gear. Buy it, get it checked, bring it up to performance levels, and save some cash.
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Ken